Syrian rebels have cemented their control of the country’s northern frontier with Turkey, as their bastions in other parts of the country came under heavy shelling.

Activists on Sunday said that opposition fighters seized the town of Khirbat al-Joz in the northwest province of Idlib after fierce clashes with regime forces.

"The fighting [a day earlier] lasted more than 12 hours and resulted in at least 40 dead among the regular forces, including five officers, and nine [rebel] fighters," the UK-based Syrian Observatory for Human Rights said.

Meanwhile, in the province of Damascus, Syrian state television said that government forces had pushed rebels out of two of their strongholds in Damascus province, Qudsaya and Hameh, where activists said that the bodies of 20 men were found.

Also on Sunday, Syrian troops pressed their offensive to retake rebel-held areas in Homs and southern villages on the border with Jordan.

In Aleppo, where fighting has raged since mid-July, the bombardment targeted the embattled district of Sakhur in the east and Kalasseh in the southwest.

Tension with Turkey

On the border with Turkey, regime forces reportedly pounded the town of Tal-Abyad in the northern province of al-Raqqa.

Nearly 80 per cent of towns and villages along the Turkish border are outside the control of Damascus, according to activists.

AFP news agency correspondents have passed through large swathes of territory in the Idlib and Aleppo provinces of northern Syria that have fallen outside government control, with residents managing their own affairs.

That followed heavy bombardments of Syrian military positions near the border since Wednesday, when a shell smashed into a Turkish town killing five civilians and sparking outrage in Ankara and a UN Security Council condemnation.

Turkey had on Friday shelled a Syrian military position south of Tal- Abyad in retaliation after a Syrian shell landed on its territory near the border.

Amid the growing tension between the Damascus and Ankara, Ahmet Davutoglu, the Turkish foreign minister, said on Saturday that Syrian Vice President Faruq al-Shaara "is a man of reason" who could replace President Bashar al-Assad as the head of a transition administration to stop the conflict in the country.

Assad replacement

Davutoglu, on the public television channel TRT, said: "Faruq al-Sharaa is a man of reason and conscience and he has not taken part in the massacres in Syria. Nobody knows the (Syrian) system better than he."

He stressed that the Syrian opposition "is inclined to accept Sharaa" as the future leader of the Syrian administration.

Sharaa, the most visible Sunni Muslim figure in the minority Alawite-led government, is trusted by the regime and was foreign minister for 15 years before becoming vice president in 2006.

Reports that he had defected in August were denied by Damascus, but some opposition leaders say he is apparently under house arrest.

Davutoglu said he was convinced that the Syrian vice president was still in Syria.

Turkey, which shares a border of 900 km with Syria and hosts nearly 100,000 Syrian refugees on its territory, openly supports rebels from the Free Syrian Army and has called for Assad's ouster.